An important limitation of the study is the fact that AUD and OPD diagnoses were register based, and that not all AUD cases will lead to registration. In this study AUD was defined both by hospitalisation with alcohol-related diagnoses and by being registered in an outpatient alcohol clinic. Post hoc analyses showed that the association between offspring and paternal AUD was strongest for registration in the WINALCO database, followed by diagnosis in the Danish Psychiatric Central Register and the Danish National Hospital Register, while the association for maternal AUD was marginally stronger for the psychiatric register than for the outpatient clinic. The relatively weak associations for the Danish National Hospital Register diagnoses may reflect substantial noise in clinical diagnoses of AUD in somatic departments.
